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Method for extracting polychlorinated biphenyls

a technology of polychlorinated biphenyls and extraction methods, which is applied in the direction of liquid organic insulators, chemical/physical processes, water/sewage treatment by ion exchange, etc., can solve the problems of environmental pollution, significant prohibition of the use of electric insulating oils containing pcbs, and toxicity of pcbs to the living body, so as to improve the extraction rate (recovery rate) of polychlorinated biphenyls

Inactive Publication Date: 2012-12-11
NAT UNIV CORP EHIME UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a method for extracting polychlorinated biphenyls from an oily liquid. The method involves adding an oily liquid to a sulfuric acid silica gel layer, heating the layer, and then cooling it. An aliphatic hydrocarbon solvent is then added to the cooled layer and passed through the layer. A silver nitrate silica gel layer and an alumina layer are used to capture the polychlorinated biphenyls. The captured polychlorinated biphenyls are then dissolved in a hydrophobic solvent and secured. The method allows for faster extraction of polychlorinated biphenyls from oily liquids.

Problems solved by technology

However, the toxicity of PCBs to the living body has been confirmed, so that in Japan, the production and import of PCBs have already been prohibited, and use of electric insulating oils containing PCBs came to be substantially prohibited.
PCBs-containing electric insulating oils and the like used in the past might cause environmental pollution during their disposal process and have thus been stored as they are until now for a long time by manufacturers of electric instruments, enterprises using such oils, and industrial waste disposers.
However, there were cases where PCBs estimated to be mixed during the production process were detected in electric insulating oils and the like manufactured after prohibition of use of PCBs, and thus some electric insulating oils used at present in electric instruments such as transformers may correspond to PCBs wastes subject to the PCB Special Measures Law.
However, the official method requires many steps of complicated treatments such as dimethylsulfoxide (DMSO) / hexane partition, sulfuric acid treatment, alkali treatment and silica gel column treatment, thus requiring a long time by day until completion and costing very high to be performed.
However, it is estimated that about 6 million electric instruments such as transformers are in use in Japan, so that when all electric insulating oils in these electric instruments are to be pretreated and analyzed by the official method, huge amounts of time and cost are required.
Accordingly, it is substantially difficult under present circumstances to subject electric insulating oils in all electric instruments to PCB screening until the time limit stipulated under the PCB Special Measures Law.
However, the substitute method described above is troublesome in preparing an extract from a sample of an object to be judged, the time necessary for treatment still remains so long as about 2 to 3 days, and the cost for pretreatment is high.

Method used

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  • Method for extracting polychlorinated biphenyls
  • Method for extracting polychlorinated biphenyls
  • Method for extracting polychlorinated biphenyls

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0118]85 mg of the electric insulating oil A and 50 μL of an internal standard substance solution for concentration calculation were added to the upper end of the first column allowed to stand such that the sulfuric acid silica gel layer became an upper layer. The sulfuric acid silica gel layer in this first column was heated at 80° C. for 30 minutes and cooled to room temperature, and then the second column was connected to the lower end of the first column. Then, 20 mL of n-hexane was supplied at a rate of 1 mL / min. to the upper end of the first column and then discharged from the lower end of the second column. After supply of n-hexane, the second column was detached from the first column, and n-hexane remaining in the second column was removed. Here, the second column was supplied with a nitrogen gas, while the second column was heated at 80° C.

[0119]Next, the second column was supplied at room temperature (20° C.) with toluene in a direction opposite to the direction in which n...

example 2

[0121]85 mg of the electric insulating oil A and 0.40 mL of isooctane were added to the upper end of the first column allowed to stand such that the sulfuric acid silica gel layer became an upper layer. The sulfuric acid silica gel layer in this first column was heated at 80° C. for 30 minutes and cooled to room temperature, and then the second column was connected to the lower end of the first column. Then, 20 mL of n-hexane was supplied at a rate of 1 mL / min. to the upper end of the first column and then discharged from the lower end of the second column. After supply of n-hexane, the second column was detached from the first column, and n-hexane remaining in the second column was removed. Here, the second column was supplied with a nitrogen gas, while the second column was heated at 80° C.

[0122]Next, the second column was supplied with toluene in a direction opposite to the direction in which n-hexane was passed, so that PCBs captured by the second column were extracted. Here, th...

example 3

[0124]An extract was obtained in the same manner as in Example 2 except that the electric insulating oil B was used in place of the electric insulating oil A (provided that similar to Example 1, 50 μL of an internal standard substance solution for concentration calculation was added to the upper end of the first column). The time taken to obtain this extract after initiation of the operation was about 2 hours. The collected extract was measured for its concentration of PCBs by the same method as in Example 1.

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Abstract

Column which includes a first column with an upper layer of H2SO4 silica gel and a lower layer AgNO3 silica gel and a second column packed with alumina, connected detachably to a lower end of the first column. An oily liquid containing polychlorinated biphenyls, is added to the upper layer and heated. An aliphatic hydrocarbon solvent is supplied to the upper layer, whereby polychlorinated biphenyls captured by the first column are dissolved in the aliphatic hydrocarbon and then flow to the second column. The polychlorinated biphenyls are captured by the alumina which is located near the inlet of the second column, which is then detached from the first column. A hydrophobic solvent is passed through the second column in a direction opposite to the direction in which the aliphatic hydrocarbon was passed, providing an extract containing the polychlorinated biphenyls dissolved in a small amount of the hydrophobic solvent.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for extracting polychlorinated biphenyls and in particular to a method for extracting polychlorinated biphenyls from a polychlorinated biphenyl-containing oily liquid.BACKGROUND ART[0002]As electric insulating oils for electric instruments such as transformers and capacitors, those consisting of mineral oils containing polychlorinated biphenyls (referred to hereinafter as “PCBs”) excellent in electrical insulation properties were generally used. However, the toxicity of PCBs to the living body has been confirmed, so that in Japan, the production and import of PCBs have already been prohibited, and use of electric insulating oils containing PCBs came to be substantially prohibited. PCBs-containing electric insulating oils and the like used in the past might cause environmental pollution during their disposal process and have thus been stored as they are until now for a long time by manufacturers of electric instruments, e...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01N30/02
CPCB01D15/00B01J20/103B01J20/3204B01J20/3236G01N30/88G01N33/2835G01N30/462Y10T436/25375G01N2030/8845G01N2030/8854Y10T436/255G01N30/6039G01N30/06G01N30/26G01N1/4055G01N1/4022G01N27/623G01N2001/4061
Inventor HONDA, KATSUHISATAKAHASHI, TOMOFUMI
Owner NAT UNIV CORP EHIME UNIV